On the verge of converting his 12th straight third round lead into victory, Singh pulled his tee shot at the par-4 13th left into waist-high weeds, ultimately leading to a tournament-costing triple bogey 7.
'I didn't play that bad, except for the drive on 13. I thought the wind would have stayed down, but it blew quite a bit,' said Singh. 'I lost the tournament right there. That took a lot out of me.'
Singh finished with a 1-over 74 and finished in a three-way tie for fifth with Adam Scott and Stewart Cink, three back of winner Stuart Appleby. He was the only player at the top of the leaderboard to be over par on the day.
Singh, who will hang on the the top spot in the world rankings despite finishing behind both Tiger Woods and Ernie Els, had led the tournament from the start. A three-putt bogey on the par-4 fourth was his first miscue of the week and may have signaled what was yet to come.
After his disaster on 13, Singh came right back with a birdie at the 14th but couldn't capitalize on either the par-5 15th or the par-5 18th.
'I tried to make birdies coming in, but it's hard making birdies on a golf course with a totally different wind direction,' said Singh. 'You're trying to force things and whenever you try to force things, they are never going to happen.'
The last time Singh blew a third round lead was at the 2001 WorldCom Classic when he also shot a final-round 74 leaving him in a tie for third.